title: “VCL Image Scripts: Post-Load, Post-Reserve, & Post-Reservation”
Scripts may be saved within VCL images which are automatically executed at specific stages of the VCL reservation process. The scripts are added by the image creator prior to saving the image. They must be located and named exactly as specified below.
For Windows image scripts, the output is saved in C:\Cygwin\root\VCL\Scripts\Logs. The name of the log file name corresponds to the name of the script. Example: C:\Cygwin\root\VCL\Scripts\Logs\vcl_post_load.log
Post-Load
Location:
- Linux: /usr/local/vcl/vcl_post_load
- Windows: C:\Windows\vcl_post_load.cmd
The post-load script will be executed every time a compute node is loaded, meaning:
- Whether or not the compute node is assigned to a user's reservation
- After a user's reservation ends and the compute node is automatically reloaded with another image
- After a compute node is reloaded with a specific image via the Manage Computers utility
The post-load script is executed after all of the standard post-load steps are performed via SSH by the management node's vcld process. For Linux images, these steps include:
- Secure the firewall to only allow access from the management node
- Configure the SSH service so access is only permitted from the management node
- Randomize the root password
- Set the node's hostname
It is important to recognize that the steps listed above to not include any steps related to the creation or configuration of user accounts intended for end user connections. The user accounts have not been created prior to the stage when the post-load script is executed.
The post-load script is useful for:
- Making changes to configuration files which require the IP address of the compute node to be known
- Registering the compute node with an external service such as for OS activation or software licensing
- Mounting external storage intended for system files or logs
Post-Reserve
Location:
- Linux: /usr/local/vcl/vcl_post_reserve
- Windows: C:\Windows\vcl_post_reserve.cmd
The post-reserve script is only executed when a user makes a reservation for an image and acknowledges the reservation by clicking the Connect button. It is executed after the standard reserve steps are performed via SSH by the management node's vcld process. These steps include:
- Add user account(s) and set passwords if applicable
- Grant access via SSH and other connect methods
- For cluster reservations, the /etc/cluster_info file is created
The post-reserve script is useful for:
- Making changes to configuration files which require the username(s) to be known
- Starting services which should only run when the compute node is available to an end user
- Configuring the firewall to allow access to a particular service
- Configuring interaction with other compute nodes assigned to a cluster by parsing the cluster_info file and modifying configuration files with information about the other cluster nodes
- Mounting external storage intended for user files
Post-Reservation
Location:
- Linux: /usr/local/vcl/vcl_post_reservation
- Windows: C:\Windows\vcl_post_reservation.cmd
The post-reservation script is executed prior to a compute node being reloaded. It does not matter if the compute node is reloaded with the same or a different image, nor does it matter if the compute node was assigned to an end user reservation or simply is being reloaded via the Manage Computers utility.
The post-reservation script is useful for:
- Stopping services
- Unregistering the compute node from external services such as a license server in order to free up a license for other users
- Removing/unregistering the node from an external shared filesystem